The present invention pertains to mobile packet data networks and more particularly to call setup methodology for dispatch data, data, and interconnect calls.
In wireless communication systems, mobile units or devices are required to operate on batteries and these mobile units will go inactive on the RF (radio frequency) channels (or dormant) after a short period of inactivity of usage for data services, usually 30 to 60 seconds. Therefore, in dispatch data, interconnect and data calls using wireless data services, both the originating and terminating mobile units must be transitioned to the active state (actually using RF resources) as part of the call setup prior to enabling the data transfer function. Once a mobile unit is in the active state, an RF (radio frequency) channel has been established and the mobile unit is able to transmit and/or receive data.
When a mobile unit is in the active state, it consumes significant amounts of RF capacity even if the user is not actually engaged in a data transfer function, as is the case when the mobile unit is in the state after the last data transfer function but before the period of inactivity has expired. These RF costs are due to overhead from power control, and in some cases dedicated pilot. When a mobile unit is in particularly good RF locations, as indicated by the Ec/Io or pilot signal strength that they detect, it will consume significantly less RF resources when it is active (on an RF channel) than will one in a bad RF location (i.e. with a poor Ec/Io).
For typical dispatch call applications, the time required for transitioning an originating mobile unit from a dormant state to the active state can be greater than 3 seconds in current implementations. An equal or greater amount of time is required to transition the terminating mobile unit from the dormant to active state, including additional time to actually page the terminating mobile unit, as is known in the art. These times do not include transmission time over the air or call processing time required by the dispatch servers. As a result, for the push-to-talk function total delay times experienced by the originating mobile unit may be 10 seconds or greater.
With long call setup times, the advantages of the dispatch service as an instant communication method is diminished. In fact, call setup times of 8 seconds or even longer may make the service non-viable in the marketplace. For example, users would prefer to use cellular (interconnect), rather than holding down the PTT button.
Accordingly, it would be highly desirable to have a method for substantially decreasing the call setup time for calls within a packet data network configuration.